Wheel lock for a vehicle

ABSTRACT

A wheel lock designed for vehicle theft prevention and comprising valve means interposed in the brake fluid line to at least one wheel brake cylinder of the vehicle. Turning a key-lock operated camshaft urges the valve means toward the closed position, blocking fluid flow through the brake line. By simultaneously or subsequently depressing the vehicle brake pedal, brake fluid under pressure opens the valve means; when the pedal then is released, the valve means closes to trap pressurized fluid between the wheel lock and the brake cylinder, thereby locking the wheels. The valve means thereafter remains closed, with the wheels locked, until disengaged by key.

United States Patent Cvetkovich 154] WHEEL LOCK FOR A VEHICLE [72]Inventor: Dejan O. Cvetkovich, 10044 San Juan Court, Fountain Valley,Calif.

[22] Filed: Aug. 28, 1970 [21] Appl. No.: 67,713

52 .s. Cl. ..137/384.6,. 137/598, 303/89, 188/353 [51] Int. Cl. ..Fl6k35/06, F16d 65/32 58 FieldotSearch ....137/384.6,598;188/353,

[561 References Cited UNITED STATES PATENTS 2,307,644 1/1943Schlumbrecht et al....1813/353.

1/1964 Duncan ..137/384.6

- [451 Aug. 8, 1972 4 Primary Examiner-Henry T. KlinksiekAttorney-Philip M. l-linderstein 57 'ABSTRACT A wheel lock designed forvehicle theft prevention and comprising valve means-interposed in thebrake fluid line to at least one wheel brake cylinder of the vehicle.Turning a key-lock operated camshaft urges the valve means toward theclosed position, blocking fluid flow through the brake line. Bysimultaneously or subsequently depressing the vehicle brake pedal, brakefluid under pressure opens the valve means; when the pedal then is.released, the valve means closes to trap pressurized fluid between thewheel lock and the brake cylinder, thereby locking the wheels.

.The valve means thereafter remains closed, with the wheels locked,until disengaged by key.

4 Claims, 4 Drawing Figures Patented Aug. 8, 1972 I N VEN TOR 05/4 0.trim away 14m Fi -922% ATTORNEYS WHEEL LOCK FOR A VEHICLE BACKGROUND OFTHE INVENTION 1. Field of the Invention The present invention relates toan improved wheel lock designed for theft prevention of a vehicle havinga fluid brake system. More particularly, the invention relates to awheel lock comprising key operated valve means interposed in the brakefluid line to at least one wheel brake of the 'vehicle, and capable oftrapping brake fluid under pressure between the valve means and thebrake cylinder to lock the wheels.

2. Description of the Prior Art Whether for joy riding or with criminalintent, the number of automobiles stolen each year continues toincrease. The problem is a serious one, not only for inconvenience tothe vehicle owner and the drain on police manpower, but also because ofthe danger resulting from unlicensed, unskilled operators driving thestolen vehicles on the roadway. Moreover, such stolen vehicles,particularly when stripped by the thief, represent a significant loss tothe vehicle insurer.

The concern raised over the increasing number of stolen vehicles inrecent years has led automobile manufacturers and others to incorporatetheft prevention devices in vehicles. For example, audible alarms havebeen utilized to indicate that the ignition key has been left in thelock after the engine has been turned off and the car door opened. Thisfeature has reduced the likelihood of leaving an ignition key in thecar, and thus made it necessary that the person stealing the car jumperor hot wire the ignition to start the car. While this is some deterrentto automobile thievery, the ignition system is relatively easy tojumper, and a considerable number of automobiles still are stolen inthis manner.

Another approach has been to provide a mechanical lock for the steeringshaft and transmission, the lock being actuated as the ignition key isrotated to the off position. This approach if efiective in that itprevents the automobile from being driven even though the engine may bestarted by jumpering the ignition system. However, complex mechanicalarrangements are required to accomplish the locking action, therebyadding significantly to the cost of the vehicle. Moreover, such systemsare not tamperproof, can be broken easily and are costly to repair.

The inventors related, copending U. S. application Ser. No. 6,246discloses an inexpensive theft deterrent device which readily can beinstalled on new or used vehicles and which will prevent the vehiclefrom being driven, even though the engine has been turned on. Thatdevice comprises a tamperproof wheel lock for a vehicle having a fluidbrake system. The device prevents theft by making it impossible to rollor propel the vehicle on its own wheels when the wheel lock has beenengaged. The present application discloses an improved wheel lock whichis similar in application and benefits, but is somewhat simpler indesign than the device disclosed in the inventors copending application.

The present invention offers a further advantage not available in thepast. In one mode of operation, when the device is engaged using a key,the vehicle wheels are not immediately locked. However, the vehiclewheels will lock the first time the brake pedal is depressed. Thus, ifengaged without brake depression, a thief may start to drive away with avehicle, but as soon as he applies the vehicle brakes, the wheels willbe locked and he will go no further.

SUMMARY OF THE INVENTION In accordance with the present invention, thereis provided a wheel lock designed for theft prevention of a vehiclehaving a fluid brake system. The wheel lock comprises key-operated valvemeans interposed in the brake fluid line to at least one wheel brake ofthe vehicle. By closing the valve means, and simultaneously orsubsequently depressing the vehicle brake pedal, brake fluid underpressure is trapped between the valve and the brake cylinder, lockingthe wheels.

In a preferred embodiment, the wheel lock is enclosed in a unitaryhousing. An inlet, an outlet and a chamber in the housing facilitatebrake fluid flow through the device under control of a valve comprisinga valve seat communicating with the inlet and a piston attached to apiston rod having a flanged member at the other end thereof. A supportmovably surrounds the piston rod with the flanged member disposed withina recess in the support. A first bias spring surrounds the rod andextends between the piston and the support. A second bias spring extendsbetween the valve seat and the support. A rotary camshaft, operated by akey-lock extending from the housing, urges the support, first spring andpiston between a valve closing position and a valve opening position.

When the camshaft is turned to the valve closing position, the supportand first spring bias the piston against the valve seat. If the vehiclebrake pedal is simultaneously or subsequently depressed, the greaterpressure on the inlet side will cause the piston and rod to movelongitudinally of the support, thereby opening the valve and permittingpassage of brake fluid under pressure. When the brake pedal thereafteris released, the valve piston will be shut tightly against the valveseat, trapping brake pressure under fluid between the closed valve andthe brake cylinder, thereby locking the wheels and preventing thevehicle from being driven or moved on its own wheels. The valve willremain shut, with the wheels locked, until opened by key-lock rotationof the camshaft and depression of the brake pedal to equalizesubstantially the pressure on both sides of the valve.

Thus it is an object of the present invention to pro vide an improvedwheel lock for a vehicle.

It is another object of the present invention to provide a device forlocking the wheels of a vehicle and including key-lock operated valvemeans interposed in the fluid line of a vehicle fluid brake system andopera tive, upon depression of the vehicle brake pedal simultaneous withor subsequent to key-actuation of the device, to trap brake fluid underpressure between the device and the vehicle wheel brake cylinder, thuslocking the vehicle wheel.

BRIEF DESCRIPTION OF THE DRAWINGS Still other objects, features, andattendant advantages of the present invention will become apparent tothose skilled in the art from a reading of the following detaileddescription of the preferred embodiment wherein:

FIG. 1 is a perspective view of a vehicle wheel lock in accordance withthe present invention, showing interconnections to the brake fluid lineof the asmciated vehicle;

FIG. 2 is a sectional view of the inventive wheel lock as seen generallyalong the line 2-2 in FIG. 1, with the camshaft oriented in the valveopening position;

FIG. 3 is a sectional view of the inventive wheel lock as seen generallyalong the line 3-3 of FIG. 2, but with the camshaft shown in the valveclosing with the valve closed; and

FIG. 4 is a sectional view of the wheel lock also as seen generallyalong the line 3-3 of FIG. 2, and shown with the camshaft in valveclosing position but with the valve open.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings,and particularly to position and FIG. 1 thereof, there is shown a wheellock designed for theft prevention of a vehicle having a fluid brakesystem. As seen therein, wheel lock 10 includes a housing 11 extendingfrom which is a pick-proof, rotary, key-operated lock 12. A key 13 isshown inserted in lock 12 so as to permit actuation of wheel lock 10;key 13 is removable and normally would be withdrawn from lock 12 afterengaging or disengaging wheel lock system master cylinder (not shown) toan inlet 18 in wheel lock 10. Such coupling may be accomplished using aconventional hex-headed fitting 19. An outlet 20 from wheel lock 10 isconnected by means of a similar fitting (not shown) to a brake fluidline 21 leading to one or more wheel brake cylinders of the associatedvehicle.

Structural details of wheel lock 10 are evident in FIGS. 2-, 3 and 4.Referring thereto, it may be seen that inlet 18 communicates with acentral opening 22 in a valve seat 22 threadingly mounted and sealedwithin housing 11. Opening 22, in turn communicates with a chamber 23,the other end of which is connected via an opening 24 to outlet 20. Theside walls of chamber 23 include one or more longitudinal grooves 23'which facilitate brake fluid flow around various components of a valve25.

Cooperating with valve seat 22 as a component of valve 25 is a valvepiston 26 typically fabricated of brake fluid resistant hard rubber suchas ethylene propylene. Piston 26 is fixedly attached to one end of apiston rod 27. Attached to the other end of rod 27 is a I flanged member28. For simplicity of construction,

piston rod 27 may be threaded, and member 28 may comprise a nut threadedonto rod 27 and peened 'to prevent relative motion between member 28 androd 27.

Surrounding piston rod 27 is a generally cylindrical support 29 havingan axial bore 30, the diameter of which is greater than the outerdiameter of piston rod 27 Support 29 also includes a recess 31 withinwhich is situated flanged end 28 of rod 27. With this arrangement,piston rod 27 is free to reciprocate or move longitudinally through borein support 29.

A first spring 32 surrounds rod 27 and extends between support 29 and amember 33 threaded to rod 27 adjacent piston 26. Member 33 firmlyretains one end of spring 32 and protects piston 26 from possibly beingdamaged by spring 32. Note that spring 32 biases piston 26 away fromsupport 29, toward a position at which flanged end 28 abuts againstsupport 29. A second spring 34 surrounds the piston rod assembly andextends between valve seat 22 and support 29.

Spring 34 biases support 29 against the cam portion 36 of a camshaft 37.

As best seen in FIG. 2, camshaft 37 is disposed within chamber 23generally perpendicular to piston rod 27. Camshaft 37 includes a firstend 38 extending into a counterbore 39 in a member 40 threaded andsealed into housing 11. The exterior surface 40a of member 40 preferablyis flush with the exterior of housing 1 1, so as to prevent tampering ofwheel lock 10 by removal of member 40. A vent hole may be provided inmember 40 to facilitate insertion of camshaft end 38 subsequent tomounting of seal 46. Theother end 42 of camshaft 37 includes a recess 43which receives a shaft 44 extending from lock 12 andoperated by key 13.A pin 45 locks camshaft 37 to shaft 44.

A pair of high pressure resistant seals 46, 47 surround camshaft ends 38and 42, respectively supported by shoulders in member 40 and housing 11.Seal 46 prevents brake fluid under pressure from getting behind camshaftend 38 and pushing it out of counterbore 39. Seal 47 prevents leakage ofbrake fluid between camshaft end 42 and housing 11. A pair of set screwsrotation of camshaft 37 from the valve opening position shown in FIG. 2to the valve closing position shown in FIGS. 3 and 4. In the valveopening position (FIG. 2), cam portion 36 of camshaft 37 is disposedtoward the bottom 11a of housing 11. Spring 34 biases support 29 againstcam portion 36, and support 29 in turn urges flanged end 28 and pistonrod 27 toward camshaft 37, thereby opening valve 25. In this valve opencondition in which piston 26 is spaced from valve seat 22, brake fluidcan flow unimpeded between inlet 18 and outlet 20. Thus, with valve 25open, the vehicle brake system operates normally.

To engage wheel lock 10, key 13 is rotated so as to bring cam portion 36of camshaft 37 to the valve closing position shown in FIGS. 3 and 4. Inthis position, cam portion 36 is situated at the top of its travel, andurges support 29 upward toward valve seat 22. As a result, spring 32 isfurther compressed and urges member 33, red 27 and piston 26 upward soas to seat piston 26 against valve seat 22. In this closed position,illustrated in FIG. 3, brake fluid flow from outlet 20 to inlet 18 isimpeded completely by closed valve 25.

If camshaft 37 is turned to the valve closing position at a time whenthe vehicle brake pedal is not depressed, brake fluid in line 21 betweenwheel lock and the wheel brake cylinders will not be under pressure, andthe wheels will turn freely. To effectuate locking of the wheels, thevehicle brake pedal is depressed either simultaneous with or subsequent.to positioning of camshaft 37 in the valve closing position. When thebrake pedal is so depressed, brake fluid in line 17 from the systemmaster cylinder will be under greater pressure than the brake fluid inline 21 between outlet 20 and the wheel brake cylinders.

This excess pressure at inlet 18 will cause valve 25 to open. That is,piston 26 and piston rod 27 will be forced downward with respect tosupport 29, as to the position illustrated in FIG. 4. During this travelof piston rod 27, flanged end 28 moves downward within recess 31 towardcamshaft 37 which still is in the valve closing position. The forceexerted by spring 32, which is compressed as piston 26 opens away fromvalve seat 22, determines in part the amount of excess brake fluidpressure necessary to open valve 25. In this regard, if the brake pedalis depressed enough to hold the vehicle at standstill, the pressure willbe sufficient to open valve 25 Once piston 26 moves to theposition shownin FIG. 4, the pressure exerted by the brake system master cylinder istransmitted to the brake fluid in line 21 between wheel lock 10 and thewheel brake cylinders. As the pressure between inlet 18 and outlet 20equalizes, bias spring 32 will urge piston 26 back toward valve seat 22.When the brake pedal next is-released, reducing the brake fluid pressurein line 17 and at inlet 18, spring 32 and brake fluid under pressure onthe outlet 21 side of valve 25 will exert force on the underside ofpiston 26, member 33 and flange end 28, forcing piston 26 firmly againstvalve seat 22. As a result, valve 25 will close, trapping brake fluidunder pressure in line 21 between wheel lock 10 and the brake cylinders,thereby locking the wheels and preventing motion of the associatedvehicle. Subsequent depression of the brake pedal will not alter thiswheel-locked condition. The vehicle brakes will remain securely lockeduntil wheel lock 10 is disengaged by (a) using key 13 to rotate camshaft37 to the valve opening position shown in FIG. 2 and (b) depressing thevehicle brake pedal with force at least equal to the existing brakefluid pressure in line 21. This will cause valve 25 to open, permittingresumption of normal vehicle brake system operation.

Wheel lock 10 can be installed on wheeled vehicles of all types,including automobiles, trucks and aircraft having either hydraulic orpneumatic brake systems. The wheel lock works satisfactorily on vehicleshaving either standard or power-assisted brake systems with either discor drum-type brakes. The wheel lock can be installed either in a singleor a dual brake system. In a.

single brake system, one wheel lock can control all wheels of thevehicle; in a dual brake system, one wheel lock can control those wheelbrakes associated with the brake fluid line in which the wheel lock isinterposed.

Although not illustrated, an interlock switch actuated by rotation ofcamshaft 37, and cooperating with the vehicle ignition switch, may beused to prevent the owner from starting the vehicle while wheel lock 10still is engaged.

Thus the inventive wheel lock 10 provides a significant deterrent to thetheft of the vehicle in which it is installed. The device is simple,inexpensive, and completely safe in operation. Moreover the wheel lockis completely tamperproof; should an attempt be made either todisconnect or disassemble the device, the brake line would be opened,leaving the vehicle without brakes.

While the invention has been described with respect to the preferredphysical embodiments constructed in accordance therewith, it will beapparent to those skilled in the art that various modifications andimprovements may be made without departing from the scope andspirit ofthe invention. Accordingly, it is to be understood that the invention isnot to be limited by the specific illustrative embodiments, but only bythe scope of the appended claims.

Iclaim:

l. A device for locking one or more wheels of a vehicle having a fluidbrake system, said device being adapted for connection in series withthe brake fluid line between the system master cylinder and at least onewheel brake cylinder, said device comprising:

a housing having a brake fluid inlet and outlet and a single, elongated,fluid chamberconnecting said inlet and said outlet,

a camshaft disposed within said chamber in said housing for rotationabout an axis transverse to the longitudinal axis of said chamber, saidcamshaft being disposed adjacent said outlet,

a valve seat in said housing and in fluid communication with said inlet,said valve seat defining one end of said chamber,

a valve piston disposed within said chamber and having first and secondopposite faces, said valve piston being adapted to reciprocate betweenan open position spaced from said valve seat and a closed position withsaid first face against said valve seat, said open and closed positionsrespectively permitting and blocking fluid communication between saidinlet and said outlet,

a piston rod having one end thereof fixedly attached to a centralportion of the second face of said valve piston and having a flangedopposite end, generally cylindrical support positioned in said chamberand having'an axial bore, said piston rod extending through said bore insaid cylindrical support and being movable longitudinally thereof, saidflanged end of said piston rod being disposed within a recess in one endof said cylindrical support, said one end of said cylindrical supportbeing situated against the cam portion of said camshaft, first biasspring positioned in said chamber surrounding said piston rod andextending between the other end of said support and said second face ofsaid piston, and a second bias spring positioned in said chamberextending between said other end of said cylindrical support and saidvalve seat, whereby rotation of said camshaft urges said cylindricalsupport, said first bias spring and said valve piston toward said closedposition, said valve piston and piston rod thereafter being movablelongitudinally of said support to said open position when the pressureat said inlet exceeds thatat said outlet, said valve brake fluid flowthrough said chamber.

' 4. In a device for locking the wheels of a vehicle having a fluidbrake system, said device including a, housing having a single interiorchamber communicating between an inlet connectable to the system mastercylinder and an outlet connectable to at least one system wheel brakecylinder, a valve situated within said chamber for controlling brakefluid flow through said device, and a key-lock actuated camshaft withinsaid'housing and movable between a valve opening position and a valveclosing position, the improvement wherein said valve comprises:

- a valve piston for selectively opening or closing said inlet, saidpiston being attached toone end'of a valve stem, a,

an annular motion transmitting member surrounding 8 said valve stem andadapted to reciprocate longitudinally thereof, 7

a first spring surrounding said valve stem and biasing said motiontransmitting member against said camshaft, said first'spring being underrelatively less compression when saidcamshaft is in said valve openingposition than when said camshaft is in said valve closing position,

means comprising an element projecting laterally from said valve stemand cooperating with said motion transmitting member for displacingsaidvalve piston toward said camshaft to open said ina let, and

second spring vsurrounding said valve stem and disposed between saidvalve piston and said motion transmitting member for urging said valvepiston to close said inlet when said camshaft is moved to said valveclosing position, said spring I being relatively uncompressed when saidcamshaft is in said valve closing position and said valve is closed,pressurized brake fluid trapped between said closed inlet and said wheelbrake cylinder preventing the associated vehicle wheel from tuming, saidpressurized brake fluid. also maintaining said piston in the inletclosing position.

II! I i i

1. A device for locking one or more wheels of a vehicle having a fluid brake system, said device being adapted for connection in series with the brake fluid line between the system master cylinder and at least one wheel brake cylinder, said device comprising: a housing having a brake fluid inlet and outlet and a single, elongated, fluid chamber connecting said inlet and said outlet, a camshaft disposed within said chamber in said housing for rotation about an axis transverse to the longitudinal axis of said chamber, said camshaft being disposed adjacent said outlet, a valve seat in said housing and in fluid communication with said inlet, said valve seat defining one end of said chamber, a valve piston disposed within said chamber and having first and second opposite faces, said valve piston being adapted to reciprocate between an open position spaced from said valve seat and a closed position with said first face against said valve seat, said open and closed positions respectively permitting and blocking fluid communication between said inlet and said outlet, a piston rod having one end thereof fixedly attached to a central portion of the second face of said valve piston and having a flanged opposite end, a generally cylindrical support positioned in said chamber and having an axial bore, said piston rod extending through said bore in said cylindrical support and being movable longitudinally thereof, said flanged end of said piston rod being disposed within a recess in one end of said cYlindrical support, said one end of said cylindrical support being situated against the cam portion of said camshaft, a first bias spring positioned in said chamber surrounding said piston rod and extending between the other end of said support and said second face of said piston, and a second bias spring positioned in said chamber extending between said other end of said cylindrical support and said valve seat, whereby rotation of said camshaft urges said cylindrical support, said first bias spring and said valve piston toward said closed position, said valve piston and piston rod thereafter being movable longitudinally of said support to said open position when the pressure at said inlet exceeds that at said outlet, said valve piston returning to said closed position when said inlet pressure is relieved and thereafter remaining in said closed position to trap pressurized brake fluid between said device and said brake cylinder and thereby preventing said wheel from turning.
 2. A device as defined in claim 1 further comprising a rotary, key-operated lock mounted in said housing and operatively connected to rotate said camshaft.
 3. A device as defined in claim 1 further comprising a plurality of longitudinal grooves in the walls of said housing defining said fluid chamber for facilitating brake fluid flow through said chamber.
 4. In a device for locking the wheels of a vehicle having a fluid brake system, said device including a housing having a single interior chamber communicating between an inlet connectable to the system master cylinder and an outlet connectable to at least one system wheel brake cylinder, a valve situated within said chamber for controlling brake fluid flow through said device, and a key-lock actuated camshaft within said housing and movable between a valve opening position and a valve closing position, the improvement wherein said valve comprises: a valve piston for selectively opening or closing said inlet, said piston being attached to one end of a valve stem, an annular motion transmitting member surrounding said valve stem and adapted to reciprocate longitudinally thereof, a first spring surrounding said valve stem and biasing said motion transmitting member against said camshaft, said first spring being under relatively less compression when said camshaft is in said valve opening position than when said camshaft is in said valve closing position, means comprising an element projecting laterally from said valve stem and cooperating with said motion transmitting member for displacing said valve piston toward said camshaft to open said inlet, and a second spring surrounding said valve stem and disposed between said valve piston and said motion transmitting member for urging said valve piston to close said inlet when said camshaft is moved to said valve closing position, said spring being relatively uncompressed when said camshaft is in said valve closing position and said valve is closed, pressurized brake fluid trapped between said closed inlet and said wheel brake cylinder preventing the associated vehicle wheel from turning, said pressurized brake fluid also maintaining said piston in the inlet closing position. 